Differences in folate-protein interactions result in differing inhibition of native rat liver and recombinant glycine N-methyltransferase by 5-methyltetrahydrofolate.
Differences in folate-protein interactions result in differing inhibition of native rat liver and recombinant glycine N-methyltransferase by 5-methyltetrahydrofolate.
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DOI：
10.1016/j.bbapap.2011.10.008
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发表时间：
2012-02
期刊：
影响因子：
--
通讯作者：
Wagner C
中科院分区：
文献类型：
--
作者：
Luka Z;Pakhomova S;Loukachevitch LV;Newcomer ME;Wagner C
甘氨酸N-甲基转移酶（GNMT）是甲基代谢的关键调控酶。在哺乳动物肝脏中，它通过使用S-腺苷甲硫氨酸甲基化甘氨酸，产生N-甲基甘氨酸（肌氨酸）和S-腺苷高半胱氨酸来降低S-腺苷甲硫氨酸水平。GNMT通过结合两个分子的5-甲基四氢叶酸（单或聚谷氨酸盐形式）/活性酶的四聚体来抑制。抑制对GNMT的N-末端缬氨酸的状态和叶酸抑制剂的聚谷氨酸化敏感。与单谷氨酸盐形式相比，五谷氨酸盐形式更有效地抑制了它。天然大鼠肝GNMT含有乙酰化的N-末端缬氨酸，并且与在E.其中N-末端未被乙酰化。在这项工作中，我们使用蛋白质晶体学方法来评估这些差异的结构基础。我们发现，在叶酸-GNMT与天然酶的复合物中，两个叶酸分子与蛋白质建立了三个和四个氢键。在叶酸-重组GNMT复合物中，仅建立一个氢键。与重组酶相比，这种差异导致叶酸对天然肝脏GNMT活性的更有效抑制。
Glycine N-methyltransferase (GNMT) is a key regulatory enzyme in methyl group metabolism. In mammalian liver it reduces S-adenosylmethionine levels by using it to methylate glycine, producing N-methylglycine (sarcosine) and S-adenosylhomocysteine. GNMT is inhibited by binding two molecules of 5-methyltetrahydrofolate (mono- or polyglutamate forms) per tetramer of the active enzyme. Inhibition is sensitive to the status of the N-terminal valine of GNMT and to polyglutamation of the folate inhibitor. It is inhibited by pentaglutamate form more efficiently compared to monoglutamate form. The native rat liver GNMT contains an acetylated N-terminal valine and is inhibited much more efficiently compared to the recombinant protein expressed in E. coli where the N-terminus is not acetylated. In this work we used a protein crystallography approach to evaluate the structural basis for these differences. We show that in the folate-GNMT complexes with the native enzyme, two folate molecules establish three and four hydrogen bonds with the protein. In the folate-recombinant GNMT complex only one hydrogen bond is established. This difference results in more effective inhibition by folate of the native liver GNMT activity compared to the recombinant enzyme.
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DOI：
10.1107/s0907444904019158
发表时间：
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影响因子：
2.2
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